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hydro phoenix 
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 Topic: TDI
Posted: February 24 2017 at 4:58pm |
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My TDI is reading 23, so I should replace my DI resin correct?
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Reefer4Ever
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Posted: February 24 2017 at 5:06pm |
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Is your TDS meter in line on your rodi unit? Most in line meters have a reading of before the DI resin and one after. Can I assume you are not using the color changing DI resin. What unit do you have? I ask all this because the membrane might be going as well.
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90 gal reef w/refugium
24 gal softie tank
11 gal nano anemone tank
5 gal fresh water
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hydro phoenix
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Posted: February 24 2017 at 5:12pm |
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The membrane is 2 yrs old. I don't use an inline TDI meter. I have a mighty might from Airwaterice.com
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phys
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Posted: February 24 2017 at 6:15pm |
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Make sure you rinse your test cup (assuming you use one) several times to make sure there are no contaniments. Then test after the di. If your resin is above 10, I usually change it. Usually I'm replacing di resin every 6 months or so.
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phys
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Posted: February 24 2017 at 6:15pm |
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Rise your cup with the water you're testing too.
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hydro phoenix
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Posted: February 24 2017 at 7:09pm |
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ok! What IS the proper point numerically when I should be changing my tubes anyways? I just put all new ones on Nov of last year except the giant membrane.
Edited by hydro phoenix - February 24 2017 at 7:11pm
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hydro phoenix
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Posted: February 24 2017 at 7:16pm |
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Now it's reading 33 and I usually use a paper or plastic cup. Something disposable.
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Krazie4Acans
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Posted: February 24 2017 at 7:28pm |
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You should generally see a reading of 25 or less after your membrane and before the DI. If it's higher than that it's time to check your water pressure change the sediment and carbon and then test again. Also make sure you are running it for at least 10 minutes before you collect water or test it. Water that sits in the unit while it's not in use will have high TDS levels anger needs to be flushed out.
If you are getting TDS higher than 5 after the DI then I would change the resin at a minimum.
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Mark Peterson
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Posted: February 24 2017 at 9:07pm |
I will bet that this is a DI Resin cartridge that has become saturated and is now releasing the impurities that it had been collecting.
To test TDS (Total Dissolved Solids) I use a glass or ceramic cup and rinse it with RO water. Anything else can contaminate the water. I also let the water run for a few minutes before checking. If there is an expansion tank, I turn that off and let the water run for longer than a few minutes. My RO water usually tests around 10 ppm. When I find it testing upwards of 20 I know it's time to change the membrane. I change the Sediment and Carbon filters about every 6 months.
A decent membrane is supposed to make 5000 gals, depending on impurities (TDS) coming in the tap water. Again depending on TDS of the water coming out of the membrane, DI resin usually lasts for 100-300 gals.
An expansion tank can also go bad. When the rubber bladder inside gets really old, it deteriorates and ruins water purity.
Aloha, Mark 
Edited by Mark Peterson - February 24 2017 at 9:19pm
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hydro phoenix
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Posted: March 01 2017 at 2:44pm |
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So should I add on another DI to my system?
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bur01014
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Posted: March 01 2017 at 3:45pm |
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A TDS of 1 ppm is when I get concerned. The reason being is we don't
know what that TDS of 1 ppm is comprised of. If its mostly copper, no
good. I am more conservative than others perhaps, but this hobby as
they say is not about keeping fish and corals, but keeping clean water.
All that being said, before your DI resin, you should be
getting a TDS reading of 1-10 ppm....any higher and you will start
burning through DI resin too fast, or faster than normal. I am leaning
towards your membrane in need of replacement. You can try another DI
resin, but a TDS >20 ppm will burn through it in a few weeks time,
depending on how much water you make.
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hydro phoenix
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Posted: March 02 2017 at 7:44am |
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My membrane though has just hit the 2 yr mark. it's supposed to last 3-5 yrs, I make 12 gallons every week. I really don't think it's the membrane. However, there are some on the board who have two DI's on their systems and that's what I think I'm leaning towards.
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hydro phoenix
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Posted: March 23 2017 at 6:57pm |
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So I think I've decided to go with two DI's. Now I just have to figure out how to get it on my mighty might.
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Lyscer
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Posted: March 24 2017 at 7:58am |
To help with figuring out how to add additional DI resin to your RO unit BRS and Spectrapure have "Addon" units that you can just plug the output of your RO unit into the DI as an "Addon".
http://spectrapure.com/RO-RODI/ADD-ONS
I have a couple of questions for you though to see if there is a larger problem at hand.
If you want to see how efficient your membrane is or to see if that could be an issue, please answer the following: 1. What is your water temperature going into your unit? 2. What is the TDS of your tap water? 3. Do you know what your water pressure is? 4. What is the TDS of the water coming straight out of your membrane after it has been running for longer than 15 minutes? 5. What is your RO Unit waste output? (Put the waste line of your RO unit into a measuring unit and time it for 60 seconds and note how much waste there was in that time period) 6. What is your RO Unit production output? (Put the production line of your RO unit directly after the membrane into a measuring unit and time it for 60 seconds and note how much production water there was in that time period - once again this is right after the membrane)
When I first started diagnosing my RO unit I found that my membranes only last about 1.5 years before fouling up so I know I have something in off going on with my source of water, but it also lets me know that I need to replace those which lowers my overall cost of DI resin because I don't burn through it as often.
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hydro phoenix
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Posted: March 24 2017 at 11:32am |
1.freezing cold 2. 108 3. no idea 6. 2/3 cup (and I see floaties)
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Lyscer
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Posted: March 24 2017 at 2:50pm |
First I apologize for the long post :).
Just based on those numbers, it seems like there is a problem with your membrane, and that there is floaty white stuff)
Based on your post above that your have the mighty mite from airwater ice (50gpd with a minimum rejection rate of 96%)
Membrane Rejection Rate Tap TDS: 108 (X) RO TDS: 32 (Y)
(X-Y) = 108-32 = 76 (X-Y) / X = 76/108 = 70.37% rejection rate
So 70.37% is what your membrane is currently rejecting, so in Filmtecs specs it should be replaced since it is below the 96% minimum.
As far as output goes, the "Acceptable" ratio of production to waste is somewhere between 1part production to 5 parts waste (1/5) and (1/3).
I can already tell that something is off with your membrane because my 90GPD unit produces about 2 3/4 cups of waste in 1 minute and since your unit does 40GPD less yet your waste is 5x mine. Your waste should theoretically be less.
Just for the sake of completeness lets figure out what your max production output should be so that we can figure out what your waste output should be.
Membrane Production Calculation Expected GPD = Rated GPD * WaterPressureCorrection * TemperatureCorrection
Since your Water Pressure is unknown we will use the average (55psi) and since your Temperature is unknown we will use my average water temperature (61F) :).
TemperatureCorrection(61) = 0.754 WaterPressureCorrection(55) = 55 / 61 = .902 Expected GPD = 50GPD * .902 * .754 = 34GPD is probably pretty close to the most you should get from your unit per day. Since the most waste you should get is 5 times the production 5 * 34 = 170Gallons of waste or 170/1440(minutes in a day) = .118(Gallons per minute)
16 cups of water per gallon .. so .118gallons per minute = 1.888 cups of waste water per minute (MAX at a 5/1 ratio with a 50GPD unit)...
TLDR; I think your membrane is bad and you should replace that before adding more resin canisters
There may be some mistakes in the math above, but based on your waste output alone, I would still think the membrane is bad.
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hydro phoenix
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Posted: March 24 2017 at 6:24pm |
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Should I get a bigger membrane? They offer a 75 membrane.
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Lyscer
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Posted: March 24 2017 at 8:47pm |
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You could go up to the 75GPD but you would have to replace the flow restrictor if you did that. So I would probably stick with the 50GPD if you have been happy with it.
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Lyscer
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Posted: April 16 2017 at 11:24am |
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Just curious on this one what you ended up figuring out.
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